Preparing halothiophenes



Dec 27, l949 H. Dv HARTOUGH ETAL 29492;@34

PREPARING HALOTHIOPHENES Filed Jan. 5l, 1947 All AT TORNEY OR AGNT Patented Dec. 27, 1949 orifice '17 Claims."

iii'v'erihbc me mureihalogenatesi. der. S aus-ylthioehenee ,-Mcreipariiclliarl bromothiopleries, and

pure. Chlolojhi.@phones;4 alkyl.. deriyatires. thereofhalogeiiswisuchsas chloririaoor -Dreiniears wel?! knownin trie art and.: proceed easilyeed rapidly.

under. normalaconditions. tomield thiopheni chlorination ,115 enectedand;particular1y, upon the relative "proportions of )thiophene Aand .chlorine Whicha-re:broughtinto;`icnntact.;

.- Attempts in ,the 'past itoseparatfe `the resulting-1 thiophene-chlorine A :reaction.. mixture. into `the various'.chlorothophenes by fractional distilla-V tion .thereofhave led to. thelevolutiono'f hydra-: gen. chloride .in considrable .quantity and.. the chlorothiophenes-Is'o obtained; 'rif .anyogwere' .nt' pure, 'ToT obtanfpure=chlorthiophenes, the origfj inail,;m'e.tho;d',I developed over :sixtyiyears: 'ago and accredited to VictorgMeyerdias heretoforegenf.

callyA been employedL method .involves heating the f crude .chlorination :rieactionzzmixture with alcoholic ,potassium hydroxide-fior :several hours; to destroy :hydrogen ..;chloride addition Y products,y followed vibyzad'ditiori 'of 'Water-and suba sequent y steam '.dist-llation. 'andV .'action'a'tion... o'f

the mixture. so Lobtained, .tolyeld the various chlorothiophenes; Azsimilarmethdd.hasilikewise been :employed for .the 4 piiriifloation .oi :the reactiomproductofithiophene .witlrfbroniine.

The above described 'fprocess,. A WhileT .yielding pure Vchlorothiophenes', haslcertain inherentdiseadvantagesewhlchzirender Lit; lfix'iapplieable furthe production of V .chlorothiophene's in .commercial quantities. Foremost of thesezdis'advantages' 'vs the'rexoessivel-y -zlorigheatmg.:tiineiof ,the crude chlorinated v thioph'eneV mixture; with :alcoholic pota-ssium jhydroxide. LThis' heatngL-.peri`od ;re= quires .i severaly 1hours;-i'dependingigupon `athepeuitent holicfpo ssihui hyd oxidelof'. the order of one daykinlorder to insure'. the complete removal of acid therefrfxml.- Thus, the processI he tofore. usedior optaining pure chlorothio ph eshas been alslow, time-consuming opera addition -tqbeingf a sllw'ndrawn-out operation,"

the aforementionedprocedure, when carried out Qnajcoinmercial pasis, s unattractive `from an @chemical-pointer view-since the .IO'eSOf alcohol. or the expenseof recoyering alcohol from the.'

spentgpotassiurn hydroxidelsolution Would greatly increase the-pyerallcost pyfp'production; Furthermora-2the'gexcessivel-y amount of fuel consumed during the'gextendedheating period of the thio-l phene-chlorinefreaction mixture with alcoholic pptassium hydroxijd'eland the labor costs which would be,..inyolved .during saidv period render the process-totally Yinadequate as v an eicerit commercial. method' for preparing pure chlorothiophenes.

,In-accordancewith thepresent invention there has. now gbeenpdiscovered, al method of preparing.

pure ,halogenated thiophenes which overcomes the di sadvantages inherent .in the process heretofore:. employed.' Broa'dlystated, the process contemplated .herein comprises bringing the crude; halogenfthiophene or halogen-alkylthophene. reaction mixture into, contact with a meta1.-water; s1urry, :fsteam-distilling the resulting` solutoneto'yield adstillatexcomposed of a Water layerand .an .organic layer, separating the two layers and distilling .thezorganiclayer so obtained to effect. Aa?fra'ctionation' lthereof into the various halogenated'thiophene derivatives.

:Ithaslbeen found` thalt by carrying out the treatment. tof crude ithiophene-.chlorine or thiophenebrominezreaction mixtures according to the above,proc'edure, lthe excessively `long heating.

- periods, such`ashaver heretoorevbeen necessary with the 1use;.,of, alcoholic potassium hydroxide, canbe. substantially .eliminated. The various halogenated:thiophenesiobtainedas a Lresult of the.;procedure:described herein are of a high degee of :purityanditheprocess .of their preparation repre'sentsian lefficientoocomparatively rapid method in :comparison .with Vthe time -consuming process. .ofthegprior art. Moreover, the method Ofzthisvinventionfisa simpleprocedure forpreparingf-p'ure vrchlorinated :or brominated thiophenes of chlorination,` thel hiephene-chlorine `reaction mixture heating period With. aloe- 3 and is particularly applicable to operations on a large scale, Since the economics of the process are extremely attractive. Thus, the method described herein eliminates the use of alcohol, heretofore deemed essential for preparing the potassium hydroxide solution used in the prior art procedure, and consequently dispenses with the need of a recovery system for said alcohol. Also',

the process of this invention permits a much.

greater amount of the pure bromoor chlorotliiophenes to be obtained in a given time as will be bubbled into thiophene or alkyl derivative thereof at a rate which will insure thorough mixing and contact of the two reactants.

compared with the method heretofore employed.

This, in turn, causes a substantial vreduction-in the expenditure required per unit of pure halothiophene obtained and hence gives rise to a tion.

It is accordingly an object of the present in,- y,

vention to provide an eiective process for preparing pure bromoor chlorothiophenes. Another object is the provision of a process for preparing pure bromoor -chlorothiophenes wherein the extensive heating period necessary to the prior art procedure can be substantially eliminated to provide a rapid, eicient process. A still further object is to alford a process for preparing pure bromoor chlorothiophenes or alkyl derivatives thereof which is adaptable for commercial production. A very important object is the provision of an economical, continuous method for obtaining pure halogenated derivatives of thiophene or alkylthiophenes from crude reaction mixtures thereof.

These and other objects which will be recognized by those skilled in the art are attained in accordance with the present invention wherein pure halogenated thiophenes or alkylthiophenes are obtained by contacting the crude mixture resulting upon the brominatin or chlorination of thiophene or an alkylthiophene with a metalwater slurry and thereafter steam-distilling the resulting solution. The distillate so obtained, composed of a water phase and an organic phase, is then separated and the isolated organic phase fractionated to yield the various halogen derivatives presentl in substantially pure form.

= As pointed out above, the relative amounts of each of the particular chlorothiophenes or bro-- mothiophenes obtained will depend to a large extent upon the degree to which the thiophene is halogenated. Generally speaking, varying amounts of the mono-, di, triand tetrahalogenated derivatives will be obtained under pracically all conditions. With a small degree of chlorination or bromination, however, the monohalogenated derivative will be the predominant halogen product. When relatively larger amounts of chlorine or bromine are contacted with thiophene, the dihalogenated product is obtained in substantial yield along with the monohalogenated product. As a general rule, as the degree of halogenation is increased, the yields of triand tetrahalogenated thiophenes correspondingly increase in proportion to the amounts o-f the monoand cli-substituted halogen derivatives. It will thus be understood that the relative amounts of each of the chlorinated or brominated derivatives of thiophene obtained in accordance with the method contemplated herein will largely depend upon the conditions under which theinitial halogenation reaction is carried out. Under the usual conditions, thiophene and halogen are contacted at atmospheric pressure and at room temperature or slightly higher. The temperature at which halogenation is effected will be at or below conditions of reaction.

The resulting crude chlorination or bromination reaction is then slowly added to a metal water slurry.. The particular metal employed `should besuiciently stable to hot water so that it will not react appreciably with water under the Moreover, the metal should be active enough to react with addition products formed during the course of the reaction but be unreactive towards thiophene and/or the halogenated thiophene derivatives present in the halogen reaction mixture. It has been found in accordance with the present invention that generally metals below aluminum and above hydrogen in the electromotive series are applicable for use in the process of the present invention. More specifically, this group of metals includes manganese, zinc, chromium, iron, cadmium, cobalt, nickel, tin, and lead. Of this group, iron and zinc are to be preferred. Generally, the metal will be present preferably in a finely divided form, such as one of the powdered metals. As a gen eral rule, the ner the state of sub-division of the metal contained in the water-metal slurry, the greater will be the ease of removal of undesirable addition products from the reaction product mixture. Addition of the halogen reaction mixture to the metal-water slurry is generally carriedout by slowly adding the halogen mixture below the surface of a hot slurry of metal and Water. Ad-

dition below the surface apparently assures better contact between the constituents and reduces mechanical carry-over. In most instances where the halogenated reaction mixture was not added below the surface of the metal-water slurry, a trace of hydrogen halide was detected in the higher boiling products. Accordingly, a preferred aspect of thepresent process is the addition of halogenated thiophene mixture to a metal-water slurry below the surface thereof. The amount of the metal contained in the particular slurry employed will vary with the initial degree of halogenation and generally the heavily halogenated thiophene mixtures will require a slurry of higher metal content to completely remove the undesirable halogen or hydrogen halide addition products formed during the course of the reaction. It will, accordingly, be understood that the amount of metal contained in the particular slurry employed herein may vary to a considerable extent, depending on the metal employed and upon the proportion of additiony products present in the crude mixture resulting from the halogenation of thiophene or alkylthiophene. It will further be understood that the concentration of metal contained in the metal-water slurry will be such as to remove completely the addition products from the crude halogenation mixture.

The solution resulting upon addition of the halogen-thiophene reaction mixture to the metalwater slurry is then subjected to steam distillation. The steam distillate obtained as a result of said distillation consists of an organic layer and an overlying water layer. The two phases are suitably separatedby mechanical means. In

some?'instancesfthorganiclayeriso obtainediis desirably dried to remove traces of Watei'ltherefrom before being subjected to fractionation. If the separation of; forganio.:-and-.Water-' phases is carefully carried .outa-however,ther-drying stepmay be eliminated. Under.'some::circumstances,1v

it may be desirable to carry out the fractionation othecrganic steam distillateoveralkalis, suon assodium or potassium hydroxide, as a further precaution* in remo'ving 'all traces" of.' hydrogen halide from the distillate: Usually; however; empjlying l'the abovefdes'cribed* technique; 'fra'c= tionation' overalkansfwllnotrgenerally be found* necessary.: Upon ffactionation of the' 'organic' steamdistillate;l any unreactedl thiophenepresL ent is'recoveredandnrayheuemsed for' further halogenatio'n: The" ri'aiogenated products obt'amdoyiactionationinclude'the mono'-, diz, tri'- arrdtetranalgenatedrthiophenesin substantially pure form: The above described" process may `b'e used` preparing pure monochlorothiophene; dichlorothiophene; tri-chlorotl'iopheneg'f tetrachiorothiophone; monobromotliiopl'ie'ne, dibromothiophene, tribromothioph'eneandtetrabromothiophene; By' employing; ari-alkyl derivative" of thiophene', such as' methyl; ethyl; 'nrop'yl, fbutyl, etc.; derivatives, the"corresponding'ipure"'chloroor bromo-co'ml pounds canfbe' prepared? Thus; the lprocess of` thisA4 invention-contemplates the preparation of' pure 2#methylimonoclilorothiophene; Z-'methyll monobromothiophene;v 2"'- me'thyl' dichlorothio: ph'ene; 3i-'meth-yl' trichl'orothiophene;` 2 ethyl inonochloroth'io'phene';Y 21- ethyl trichlorothiophene; 3 ethyl dichlorothiophene 2"- propy1 monobromothi'ophene 2*- -p'ropyl-'trichlorothiophone, and tlelike;4`

' The process ofjt'liis invention" is -particularly' adaptable'A for continuous pperat'ronand .a suit'- abl'e Aapparatus f for' "carrying out a continuous process -is l'shown-in the-'attached 'drawingwhere' in thiophenefis continuouslymchlorinated' to "yield therfvarious chlorinated.' thiophenes' Referring more particularly to thenw diagrarng-thiopheneish-introduced* l'through conduit I to react'orZL and' chlorine is introduced" thr'ougiry conduit 3 'and'iis permitted to "-bubbleu'lpwa'rds" through theV down"-i ward eounterflowing' *thiophene They amountofchlorine added' toA` `the-reactor "-is :measured 'by a rotameter #unser/tedv v'in'- line -3 The-'reactor isl furnished withl a venti tolr'e'move -gaseous products produced fdurinrgf the course nof fthe chlorina tion -reacton 'The resultingf crudeethiop'hene4 chlorine reaction mixture-hows from' the 'bottom ofifthefreaotor through# outlet '6 and *passes -below theA surfaceso afrnetal-waten slurry contained iifrf-vesselei'l, therate-*offfloW-being suitably-'conl1 imolleell by--'valve-' 8.j -A AVstr'e'anfr of f the metallic slurry is supplied vto'theaforesaid vessel'through inletf -and the resulting metal chloride solution isi-withdrawnthrough? outlet f l0; Steam is conti-nuously"suppliedV to the mixture of chlorinated thiophene and-l metalslurry/ throughv conduit H, 'eiecting a steam' 'distillation' ofthe mixture'con-e tained''in-thefvesselfandthe overhead from said distillation `passes through outlet Ha and condenser =I'2vlto,lsettling'ltank I3 wherein the heavier organic materials `contained in the distillate settletoJ-t'he bottmfof the tank while Water, beingifthekv lighter constituent in the distillate, frms-alayer overlying the yheavier organic phase. -Anstre'am'Y-lof water-vis continuously withdrawn from the .upperi' portion fof ithefsettling tank throughoutlt Mifwhile a'lstream-'of the organic .layerl is withc'hf'awn@from the bottom-'ofthe set'- 1 overhead through@ outlet 18H# v action mixture n was i V15h-3figrarnsi rample 1 Y One thousand grams of thiophene (11.9 mcjhlskv were reacted at a temperature of about 30 C. with gaseous chlorine'until the weight of the re- Thet chlorine Wasfvmeasured -byfa -rotam'eter and' wasequiv'alerit'- to 1.16 moles of yclilorineperIrl41'e-"of thiophe'nar One Vthousand 'gra-ms for' the reaction :product 'were' added in lslow-s'l'lrearn tota' fhot 'zincwater slurry. containing. gr'amsf of yzinc ipowd'er' and'-` 11.500? millilitersof w-ater'. y The-.mixture fwas'continu-f ous'ly steam-distilled@ remove' the volatileinae terials therefrom. Thef'or'gani'c".phaseof th resulting steam distillatey fWaS' 1- senars'ited;l .'diiedl over-fsodium sullaterand fractionatedilto give' the following:

lPer cent 1Q4fgra'ms thiophene (recovered) 16 397 gramsrnonochl'orothiophene v 43 148 grams dichlorthiophene 1-2` Yields were based on the weight of thiophene. used.

Example.- 2:

One thousand` six hundred eightyfthree grams of thiophene l(20 moles) were reacted ataAtem-I perature of"25435 Cl'with gaseous chlorine until 20`moles of 'chlorine had been added.` The weight; oit'he crude reaction' product was 2,495'grams. Four' hundred' grains' or `this reaction" product' were added dropwi'se to a hot'slurryof 150.gra'nds' of zinc'dust and 21,000" milliliters' of Water, and`4 the'vol'atile materials were'v continuously steani`- distilled therefrom.'v Theorganie 'phase 'ofv the resulting steam" distillate `vwas sepa-'rated"`froiri1tliev water that had Ydistilled andwasfthen fr'actionil ated to `give -the following:

Per cent 57 vgrains ythiophene (recovered) VV21 193 grams .monochlorothiophene' f51 40 grams dichlorothiopheneA a.- e v r.8

Example 3 ne thousand six hundred eighty-three grams of thiophene (20 moles) were reacted at a temperature of 25-35 C. with gaseous chlorine until 20 moles of chlorine had been added, The weight of the crude reaction mixture was 2,495 grams. Four hundred grams of this reaction product were added to a hot slurry of 150 grams of zinc powder and 1500 milliliters of water over a period of 50 minutes, and the volatile materials were continuously steam-distilled therefrom. The organic phase of the resulting steam distillate was separated and collected at about room temperature, passed through a vessel surrounded by a Dry Ice-acetone bath, and then passed through a lead acetate solution. No distillate collected in the vessel surrounded by the Dry Ice-acetone bath, indicating an absence of such volatile gases as would be collected there. lead sulfide was formed in the lead acetate solution, indicating a minute amount of rupture of the thiophene ring, leading to hydrogen sulde formation. The organic distillate was separated, dried over sodium sulfate and fractionated to give the following:

Per cent 62 grams thiophene (recovered) 22 182 grams monochlorothiophene 48 66 grams dichlorothiophene 14 Yields were based on the weight of thiophene used.

Example 4 One thousand six hundred eighty-three grams of thiophene (20 moles) were reacted at a temperature of 25-35" C. with gaseous chlorine until 20 moles of chlorine had been added. The weight of the reaction product was 2495 grams. Four hundred grams of this reaction product were added to a hot slurry containing 150 grams of iron powder and 1,500 milliliters of water over a period of 1 hour. The volatile material present was continuously steam-distilled from the reaction mixture. The organic phase of the resulting steam distillate was separated, dried over sodium sulfate and fractionated to give the following:

Per cent 52 grams thiophene (recovered) 19 178 grams monochlorothiophene 47 57 grams dichlorothiophene 12 Yields were based on the weight of thiophene used.

Example 5 One thousand six hundred eighty-three grams of thiophene moles) were reacted at a temperature of -35 C. with gaseous chlorine until the weight of the reaction mixture was 2495 grams. The chlorine was measured by a rotameter and the amount of chlorine added was equivalent to 1 mole of chlorine per mole of thiophene. Four hundred grams of the resulting thiophene-chlorine reaction product mixture were heated under reux with stirring with 1000 grams of a 10 per cent alcoholic potassium hydroxide solution for a period of 24% hours. The precipitated salt obtained was removed by filtration. The resulting ltrate was diluted with water and the organic material which separated was removed. The remaining Water layer was extracted twice with petroleum ether and the extracts so obtained were added to the organic material. The organic materials were then dried A total of 0.4 gram of over sodium sulfate and fractionated to give the following:

Per cent 40 grams thiophene (recovered) 14 162 grams monochlorothiophene 43 grams dichlorothiophene 14 Yields were based on the weight of thiophene used.

It is to be noted, in comparing the results of the examples illustrating the method of the present invention with the process previously used, as illustrated by Example 5, that in order to obtain substantially the same yields of products, it was necessary, in using the prior art method, to treat the crude chlorination mixture with alcoholic potassium hydroxide for an extended period. This excessively long heating period has been eliminated by the method of this invention, thereby providing a rapid and eicient procedure for preparing pure halothiophenes.

We claim:

1. A method of preparing pure'halogenated derivatives of a material selected from the group consisting of thiophene and alkylthiophene, comprising contacting said material with a halogen selected from the group consisting of chlorine and bromine, adding the resulting halogenated mixture to a slurry of water and a metal lying below aluminum and above hydrogen in the electromotive series, steam-distilling the mixture so obtained, separating the Water phase of the resulting distillate from the organic phase and fractionating said organic phase to yield pure halogenated derivatives.

2. A method of preparing pure halogenated derivatives of a material selected from the group consisting of thiophene and alkylthiophene, comprising contacting said material with a halogen selected from the group consisting of chlorine and bromine, adding the resulting halogenated mixture below the surface of a slurry of water and a metal lying below aluminum and above hydrogen in the electromotive series, steam-distilling the mixture so obtained, separating the water phase of the resulting distillate from the organic phase and fractionating said organic phase to yield pure halogenated derivatives.

3. A method of preparing pure halogenated derivatives of a material selected from the group consisting of thiophene and alkylthiophene, comprising contacting said material with a halogen selected from the group consisting of chlorine and bromine, adding the resulting halogenated mixture to a slurry of water and zinc, steam-distilllng the mixture so obtained, separating the water phase of the resulting distillate from the organic phase and fractionating said organic phase to yield pure halogenated derivatives.

4. A method of preparing pure halogenated derivatives of a material selected from the group consisting of thiophene and alkylthiophene, comprising contacting said material with a halogen selected from the group consisting of chlorine and bromine, adding the resulting halogenated mixture to a slurry of water and iron, steamdistilling the mixture so obtained, separating the water phase of the resulting distillate from the organic phase and fractionating said organic phase to yield pure halogenated derivatives.

5. A method of making pure chlorothiophenes, comprising contacting a material selected from the group consisting of thiophene and alkylthiophene with chlorine, adding the resulting chlorinated mixture to a slurry of Water and a metal :lyingbelowalumimimiaxrdabove#hydrogen inrthle phenev with: chlorine, vadding the resulting. chlof lrinated .mixtureloelowl the :surface of a slurryr-of water:- and; a` metal lying-1.` below-.- aluminum;` and above hydrogen in," the electromotive'l series, steam=distillingthei mixture.. so: obtained;Y sepa:- rating the waterfphase-fof; the .resultingrdistillate from-the organicphase andtfractionating;saidor- -ganic Yphaseito ,fyield:purezchlorinated':derivatives. c 7. Amethodfof makingzpure;chlorothiophenes, comprising contacting material selected.` from the. group; consisting, oftliiophene and alkylthiophene with-chlorine, ,adding'a the resulting chlorinated mixture to a slurry ofwater and zinc, steam-distilling the mixtureso-obtained, separating the water phase., of: the.. resulting distillate from the organic phase and fractionating-saidorganic phase to yield pure chlorinated derivatives.

8. A method Aof 'makingpure chlorothiophenes, comprising contactinga material selectedfrom the group consisting-offtlfiio'plierre and=alkylthiophene with chlorine, adding the resulting chlorinated mixture to a slurry of water and iron, steam-distilling the mixture so obtained, separating the water phase of the resulting distillate from the organic phase and fractionating said organic phase to yield pure chlorinated derivatives.

9. A continuous process of preparing pure halogenated derivatives of a thiophene reactant selected from the group consisting of thiophene and alkylthiophene, comprising continuously contacting said material with a halogen selected from the group consisting of chlorine and bromine, flowing a stream of the resulting halogenated mixture into a slurry of Water and a metal lying below aluminum and above hydrogen in the electromotive series, continuously steamdistilling the resulting mixture and condensing the overhead ensuing therefrom to yield an organic distillate with an overlying water layer, withdrawing a stream of said organic distillate and fractionating the same to recover unreacted thiophene constituent therefrom, fractionally distilling the bottom product from the aforesaid fractionation to yield pure halogenated derivatives of the initial thiophene reactant.

10. A continuous process of preparing pure halogenated derivatives of a thiophene reactant selected from the group consisting of thiophene and alkylthiophene, comprising continuously contacting said material with a halogen selected from the group consisting of chlorine and bromine, flowing a stream of the resulting halogenated mixture into a slurry of water and a metal lying below aluminum and above hydrogen in the electromotive series, continuously steamdistilling the resulting mixture and condensing the overhead ensuing therefrom to yield an organic distillate with an overlying water layer, withdrawing a stream of said organic distillate and fractionating the same to recover unreacted thiophene constituent therefrom, recycling said constituent to further contact with halogen, fractic-nally distilling the bottom product from the aforesaid fractionation to yield pure halogenated derivatives of the initial thiophene reactant.

11. A continuous process of preparing pure lil) halogenated.derivativessofi a; thiophenef'reacta-nt selected from the; group `'.consisting-of 'thiophene and' alkylthiophene, comprisingsi continuously contactingsaidz'material with a halogen selected from the group; consisting fof chlorine; and bromine, flowing aastream ofthe rresulting halo- 'genated mixturegbelowifthef Surfacefofaslurry of water and'Y a'. metal lying; below'.` aluminum and above;v hydrogen in ,thef electromotive series, continuously steaindistilling the 3'resulting mixture and condensing; the overheadrensumg therefrom to yieldzan orga-nicdistillate with-an1overlying iwater: layen. withdrawing'.- a streamul ofi saidorganic distillate; and' fractionating the; same to recover. unreactedc thiophene constituentthere;- from, fractionally distilling the bottom,- product from the:Y aforesaid fractionationi to: yield pure halogenated derivativesv of :the v initial thiophene reactant..

12. A continuous process.-A of prepari-ng..Y pure lfialogenated:` derivatives of al thiophene ,reactant selectedfromv the.'A grmipA consisting; of thiophene and; alkylthiophenaa. comprising:n continuously contacting said imaterial with .a 'i halo-gen, ,selected from the. groupl consisting of'y chlorineandfbroimine' flowing a stream: of the. resulting.- halo,- genated mixture into: axslurry ofwater andzinc, continuously steam-distilling thezresultingymixture and .condensing theoverheadzensuing there;- from to yield an organic distillate with an overlying water layer, withdrawing a stream of said organic distillate and fractionating the same to recover unreacted thiophene constituent therefrom, fractionally distilling the bottom product from the aforesaid fractionation to yield pure halogenated derivatives of the initial thiophene reactant.

13. A continuous process of preparing pure halogenated derivatives of a thiophene reactant selected from the group consisting of thiophene and alkylthiophene, comprising continuously contacting said material with a halogen selected from the group consisting of chlorine and bromine, flowing a stream of the resulting halogenated mixture into a slurry of water and iron, continuously steam-distilling the resulting mixture and condensing the overhead ensuing therefrom to yield an organic distillate with an overlying water layer, withdrawing a stream of said organic distillate and fractionating the same to recover unreacted thiophene constituent therefrom, fractionally distilling the bottom product from the aforesaid fractionation to yield pure halogenated derivatives of the initial thiophene reactant.

14. A continuous process of preparing pure chlorothiophenes, comprising continuously contacting a material selected from the group consisting of thiophene and alkylthiophene with chlorine, flowing a stream of the resulting chlorinated mixture into a slurry of water and a metal lying below aluminum and above hydrogen in the electromotive series, continuously steam-distilling the resulting mixture and condensing the overhead ensuing therefrom to yield an organic distillate with an overlying water layer, withdrawing a stream of said organic distillate and fractionating the same to recover unreacted thiophene constituent therefrom, fractionally distilling the bottom product from the aforesaid fractionation to yield pure chlorinated derivatives of the initial thiophenev reactant.

15. A continuous process of preparing pure chlorothiophenes, comprising continuously contacting a material selected from the group consisting of thiophene and alkylthiophene with chlorine, owing a stream of the resulting chlorinated mixture below the surface of a slurry of water and a metal lying below aluminum and above hydrogen in the electromotive series, continuously steam-distilling the resulting mixture and condensing the overhead ensuing therefrom to yield an organic distillate with an overlying water layer, withdrawing a stream of said organic distillate and fractionating the same to recover unreacted thiophene constituent therefrom, fractionally distilling the bottom product from the aforesaid fractionation to yield pure chlorinated derivatives of the initial thiophene reactant.

16. A continuous process of preparing pure chlorothiophenes, comprising continuously contacting a material selected from the group consisting of thiophene and alkylthiophene with chlorine, owing a stream of the resulting chlorinated mixture into a slurry of water and zinc, continuously steam-distilling the resulting mixture and condensing the overhead ensuing therefrom to yield an organic distillate with an overlying Water layer, withdrawing a stream of said organic distillate and fractionating the same to recover unreacted thiophene constituent therefrom, fractionally distilling the bottom product from the aforesaid fractionation to yield 'pure chlorinated derivatives of the initial thiophene reactant. f

17. A continuous process of` preparing pure chlorothiophenes, comprising continuously contacting a material selected from the group consisting of thiophene and alkylthiophene with chlorine, flowing a stream of the resulting chlorinated mixture into a slurry of water and iron, continuously steam-distilling the resulting mixture and condensing the overhead ensuing therefrom to yield an organic distillate with an overlying water layer, withdrawing a stream of said organic distillate and fractionating the same to recover unreacted thiophene constituent therefrom, fractionally distilling the bottom product from the aforesaid fractionation to yield pure chlorinated derivatives of the initia1 thiophene reactant.

HOWARD D. HARTOUGH. HARRY L. COONRADT.

REFERENCES CITED The following references are of record in the le of this patent:

Ber., 17, '794-5 (1884) 19, 650 (1886). Weygand, Organic Preparations, page 77. Interscience Publishers, 1945. 

